Date   

SW Radiogram program available

 

Hello to all the digital folks out there.
 
A new program for the Shortwave Radiogram broadcasts has now been posted on the SW Radiogram website. 
 
If you're new to decoding digital, this is a pretty nice way to get your feet wet. You can use your desktop or laptop, or you can use an Android device such as a smartphone or tablet. You can find links to the SW Radiogram website, software for decoding, and wiki articles with extensive details and help at: http://www.udxf.nl/events.html.  
 
If you'd like to see a list of web receivers (which are often reported as being used), receiver, transceiver and SDR applications and more, take a look at the SW Radiogram gateway at https://wiki.radioreference.com/index.php/Shortwave_Radiogram_Gateway
 
Help is also available on Facebook and Twitter. The SW Radiogram website has the links. 
 
Radio Northern Europe International has announced its new schedule for program 21.  
See https://rnei.org/2021/09/02/radio-northern-europe-international-show-21-announcement/ 
 
KBC Radio in the Netherlands also uses digital modes in their broadcasts.  They usually announce the frequency, time and modes they are going to use 
on their Facebook page. https://www.facebook.com/TheMightyKbc
 
Here's hoping for good propagation 


New release of MULTIPSK 4.45.3 (QR Code in "B/W24" SSTV mode) #Multipsk

Patrick Lindecker
 

New release of MULTIPSK (4.45.3)

 

Pour les francophones: la version en français de ce message se trouve sur mon site (http://f6cte.free.fr). Il suffit de cliquer sur le lien "Principales modifications (courriel avertissant de la sortie de la nouvelle version)".


Hello to all Ham and SWL,

 

The new releases of Clock (1.11.11) and MultiPSK (4.45.3) are on my Web site (http://f6cte.free.fr/index_anglais.htm).
The mirror site is Earl's, W8BR: https://www.paazig.net/f6cte/MULTIPSK_setup.exe

The MD5 signature of the downloaded MULTIPSK_setup.exe file to, possibly, check (with WinMD5 for example), that the downloading works without error, is equal to:

8a907eb9187f25843e41f2610851d728

Multipsk associated to Clock are freeware programs but with functions submitted to a licence (by user key).

 

Modifications of Clock 1.11.11: the HBG station has been removed and FRANCE-INTER is now called "FLE".

 

The main improvement of MULTIPSK 4.45.3 is the following:

 

Insertion of a QR Code in SSTV, sub-mode "B/W24"


In the B/W24 sub-mode (black and white format, permitting the transmission of a 320x240 pixels picture in 24 seconds), it is proposed to insert a QR Code label. This one, of normal or small size, can code up to 47 characters. At reception, this QR Code label will be decoded, stored and the Ham position (Locator) possibly displayed on a map. This label can also, of course, be decoded by a QR Code application installed on a PC, a tablet, or a mobile phone.

 

The SSTV mode and, consequently, the QR Code are freeware, so without time limitation.

About the QR Code implemented in Multipsk, see general specifications below, as well as instructions to operate QR Code in RX/TX.

 

Other improvements:

 

·                     Possibility to scroll the fax image using the mouse wheel,

·                     Multipsk can be used as a VLF (Very Low Frequencies, 0 to 24 kHz) receiver on the sound card, the AF signal having been previously filtered and amplified, then directed to the microphone sound card input. In this case, the HF frequency can be forced to 0 Hz by clicking on "->0".

·                     Possibiliy, in EPIRB, to fix one error (on a bit) or none. In this last case, the probability to decode a not valid frame becomes extremely weak.  Moreover, not valid positions are detected.

·                     Addition of the "No duplicate" option in POGSAG, so as not to display the successive repetitions of the same message.

·                     Update of the VDL2_Ground_Stations.txt (for the VDL2 mode). Thanks to Sergio. Note the extension to 5000 lines of this file.

 

Note about translation of Multipsk.exe and Clock .exe:  the 4.45.2 version of Multipsk has been translated to Spanish by Joachin (EB4Z), from French.

See: http://f6cte.free.fr/Translation_files.htm.

 

 

73

Patrick

 

Particular specifications of the QR Code used by Multipsk in the "B/W24" sub-mode

 

In the B/W24 sub-mode (black and white format, permitting the transmission of a 320x240 pixels picture in 24 seconds), it is proposed to insert a QR Code label. This one, of normal or small size, can code up to 47 characters. At reception, this QR Code label will be decoded, stored and the Ham position (Locator) possibly displayed on a map. This label can also, of course, be decoded by a QR Code application installed on a PC, a tablet, or a mobile phone.

 

Multipsk codes the QR Code according to the "ISO/IEC 18004 - First edition 2000-06-15" standard. The QR Code has been invented by Denso-Wave and made public in 1999.

The specificities of the QR Code used by Multipsk are:

·                     The version 2 (25 x 25 modules) is the sole used, but the 4 correction levels (H, Q, M and L) are used.

·                     The "Alphanumeric" mode is the sole used.

·                     To simplify the coding and the decoding, the sole mask used for data is the one which carries the conditon "(i+j) mod 2=0", i.e. the "Mask Pattern Reference=000" according to the table 23 of the ISO reference.
The other masks are not used.

·                     The width of the quiet zone is standard and equal to 4 modules.

 

Note: these specificities permit to maximize the QR Code decoding quality, by limiting the number of possibilities.

 

The QR code is located in the lower right corner of the SSTV picture (320x240 pixels in B/W24).

A module is equal to 6 x 6 pixels for the standard format and 3 x 3 pixels for the small format.

 

Use of the QR Code in the sub-mode B/W24

If snapshots don't appear, directly download the file: http://f6cte.free.fr/Use_of_the_QR_Code_in_the_SSTV_sub-mode_BW24.pdf

It is described a basic use. For the other options in RX and in TX (as the header or not...), see the different possibilities in the SSTV manual.

It is reminded that SSTV frequencies are, in kHz: 3730 (LSB), 7035 (LSB), 14230 (USB), 21340 (USB), 28680 (USB) and 144500 (FM).

Start Multipsk, click on "RX/TX screen", then on the "SSTV" mode and finally on the "B/W24" sub-mode.

To transmit a QR Code

Confirm that the "QR Code insertion" button is pushed. Enter in the editor, without carriage returns and separating words with spaces, as a minimum, your Ham call sign, first name and Locator, as for example "FX9XYZ PIERRE JN18FT".
Try to limit your text to 20 characters, so as to keep with the best correction level (H) and so to be confident about the good decoding of your QR Code.

Add the same text in the "SSTV TEXT" editor and position it in the upper part of the picture. You can store this picture, using the "diskette" icon, in a FX9XYZ.BMP file (for example). Once done, the next time you will only have to load this file.

Transmit this picture clicking on the "Transmit" button.

You can choose between a standard QR Code format and a small one. The second one is 4 times smaller than the standard format, but it is also 4 times less sensitive (in terms of Signal to Noise ratio).
See the difference below.

To receive a QR Code

Each time you want to receive a new SSTV picture, click on the "Synchro" button. For completely automatized SSTV reception, see the SSTV manual ("Auto Save" and "Auto synchro" options).
The synchronization and reception are automatic. Of course, you are going to receive all SSTV pictures, not only the ones with the QR Code.

Click on the "Pos" button to see on a map, the positions from where the SSTV pictures are transmitted. Note that the received QR Code is stored and is accessible by clicking on the "QSO" button

Note that Hams receiving the QR Code with other programs (Mixw for example), will decode this one using a QR Code application installed on a PC, a tablet, or a mobile phone.

Example

Suppose that another Ham receives your SSTV picture. In the snapshow below you will find, to the left, the transmitted picture and, to the right, the same picture received, with decoded text at the bottom and the Ham position on the map.

 

 


VARA Monitor Lock -ALL User's invited to test / Trial the new version

Graham
 

Monitor Lock ,  the  fix is  in V 4-4-6  

Duplicating  the monitor freeze issue proved illusive , could be a combination of  platform and 
windows build ,not being able to  induce the  fault condition, the  function has been  
audited  and  re-released 

Version 4-4-6 , now available for  download ,

ALL   User's  invited to test / Trial  the  new version 

73-Graham
g0nbd 


KBC Radio in the Netherlands also sends digital

 

They usually announce the frequency, time and modes they are going to use on their Facebook page.  

https://www.facebook.com/TheMightyKbc

I will add this in future announcements.

Mike


SW Radiogram program available

 

Hello to all the digital folks out there.
 
A new program for the Shortwave Radiogram broadcasts has now been posted on the SW Radiogram website. 
 
If you're new to decoding digital, this is a pretty nice way to get your feet wet. You can use your desktop or laptop, or you can use an Android device such as a smartphone or tablet. You can find links to the SW Radiogram website, software for decoding, and wiki articles with extensive details and help at: http://www.udxf.nl/events.html.  
 
If you'd like to see a list of web receivers (which are often reported as being used), receiver, transceiver and SDR applications and more, take a look at the SW Radiogram gateway at https://wiki.radioreference.com/index.php/Shortwave_Radiogram_Gateway
 
Help is also available on Facebook and Twitter. The SW Radiogram website has the links. 
 
Radio Northern Europe International has announced its new schedule for program 21.  
See https://rnei.org/2021/09/02/radio-northern-europe-international-show-21-announcement/ 
 
Here's hoping for good propagation 


Updated list of RS ID - new RSID-EOT #RS ID #rs

Patrick Lindecker
 

Hello to all,

 

Below it will found the updated list of RS ID, with the new RSID-EOT for “End Of Transmission”, to re-enable a squelch or notify a completion of transfer, for example (used by Fldigi).

 

UPDATED LIST OF RS ID

 

IF NUMBER=1 THEN MODE:='BPSK31' ELSE

IF NUMBER=2 THEN MODE:='BPSK63' ELSE

IF NUMBER=3 THEN MODE:='QPSK63' ELSE

IF NUMBER=4 THEN MODE:='BPSK125' ELSE

IF NUMBER=5 THEN MODE:='QPSK125' ELSE

IF NUMBER=7 THEN MODE:='PSKFEC31' ELSE

IF NUMBER=8 THEN MODE:='PSK10' ELSE

 

{"MT63" parameter 1 parameter 2 (parameter 1: "500", "1000" (1000 Hz) or "2000" (2000 Hz),

  parameter 2: "LG" (Long), "ST" (Short) or "VST" (Very short)

Example: MT63-1000-LG}

IF NUMBER=9 THEN MODE:='MT63-500-LG' ELSE

IF NUMBER=10 THEN MODE:='MT63-500-ST' ELSE

IF NUMBER=11 THEN MODE:='MT63-500-VST' ELSE

IF NUMBER=12 THEN MODE:='MT63-1000-LG' ELSE

IF NUMBER=13 THEN MODE:='MT63-1000-ST' ELSE

IF NUMBER=14 THEN MODE:='MT63-1000-VST' ELSE

IF NUMBER=15 THEN MODE:='MT63-2000-LG' ELSE

IF NUMBER=17 THEN MODE:='MT63-2000-ST' ELSE

IF NUMBER=18 THEN MODE:='MT63-2000-VST' ELSE

 

IF NUMBER=19 THEN MODE:='PSKAM10' ELSE

IF NUMBER=20 THEN MODE:='PSKAM31' ELSE

IF NUMBER=21 THEN MODE:='PSKAM50' ELSE

IF NUMBER=22 THEN MODE:='PSK63F' ELSE

IF NUMBER=23 THEN MODE:='PSK220F' ELSE

 

{"CHIP 64" parameter 1 (parameter 1: "64" or "128"), Example: CHIP-64}

IF NUMBER=24 THEN MODE:='CHIP-64' ELSE

IF NUMBER=25 THEN MODE:='CHIP-128' ELSE

 

IF NUMBER=26 THEN MODE:='CW' ELSE

 

{"CCW" parameter 1 parameter 2 (parameter 1: "OOK" or "FSK",

   parameter 2: "12" (12 wpm), "24" (24 wpm) or "48" (48 wpm)

  Examples: CCW-OOK-12 or CCW-FSK-24}

IF NUMBER=27 THEN MODE:='CCW-OOK-12' ELSE

IF NUMBER=28 THEN MODE:='CCW-OOK-24' ELSE

IF NUMBER=29 THEN MODE:='CCW-OOK-48' ELSE

IF NUMBER=30 THEN MODE:='CCW-FSK-12' ELSE

IF NUMBER=31 THEN MODE:='CCW-FSK-24' ELSE

IF NUMBER=33 THEN MODE:='CCW-FSK-48' ELSE

 

{Pactor1 ARQ not RX/TX in Multipsk 4.1.1}

IF NUMBER=34 THEN MODE:='PACTOR1-FEC' ELSE

 

{"PACKET" parameter 1 (parameter 1: "300" (bauds) or "1200" (bauds)),Example: PACKET-300}

IF NUMBER=35 THEN MODE:='PACKET-300' ELSE

IF NUMBER=36 THEN MODE:='PACKET-1200' ELSE

 

{"ASCII" parameter 1 (parameter 1: "7" (7 bits) or "8" (8 bits)), Example: ASCII-7}

IF NUMBER=37 THEN MODE:='ASCII-7' ELSE

IF NUMBER=38 THEN MODE:='ASCII-8' ELSE

 

{"RTTY" parameter 1 (parameter 1: "45" (45 bauds), "50" (50 bauds), "75" (75 bauds)), Example: RTTY-45}

IF NUMBER=39 THEN MODE:='RTTY-45' ELSE

IF NUMBER=40 THEN MODE:='RTTY-50' ELSE

IF NUMBER=41 THEN MODE:='RTTY-75' ELSE

 

IF NUMBER=42 THEN MODE:='AMTOR FEC' ELSE

 

{"THROB" parameter 1 (parameter 1: "1" (1 baud), "2" (2 bauds) or "4" (4 bauds)), Example: THROB-2}

IF NUMBER=43 THEN MODE:='THROB-1' ELSE

IF NUMBER=44 THEN MODE:='THROB-2' ELSE

IF NUMBER=45 THEN MODE:='THROB-4' ELSE

 

{"THROBX" parameter 1 (parameter 1: "1" (1 baud) or "2" (2 bauds)), Example: THROBX-2}

IF NUMBER=46 THEN MODE:='THROBX-1' ELSE

IF NUMBER=47 THEN MODE:='THROBX-2' ELSE

 

{"CONTESTIA" parameter 1 parameter 2 (parameter 1: "4" (4 tones),  "8" (8 tones), "16" (16 tones), "32" (32 tones), parameter 2: "250" (B=250 Hz), "500" (B=500 Hz) or "1000" (B=1000 Hz))...same parameters as OLIVIA

  Examples: CONTESTIA-32-1000 or CONTESTIA-8-500

  Note: the following are the main Contestia modes:

  CONTESTIA-4-250, CONTESTIA-4-500, CONTESTIA-8-250, CONTESTIA-8-500, CONTESTIA-16-500, CONTESTIA-16-1000, CONTESTIA-32-1000}

IF NUMBER=49 THEN MODE:='CONTESTIA-8-250' ELSE

IF NUMBER=50 THEN MODE:='CONTESTIA-16-500' ELSE

IF NUMBER=51 THEN MODE:='CONTESTIA-32-1000' ELSE

IF NUMBER=52 THEN MODE:='CONTESTIA-8-500' ELSE

IF NUMBER=53 THEN MODE:='CONTESTIA-16-1000' ELSE

IF NUMBER=54 THEN MODE:='CONTESTIA-4-500' ELSE

IF NUMBER=55 THEN MODE:='CONTESTIA-4-250' ELSE

 

IF NUMBER=56 THEN MODE:='VOICE' ELSE

IF NUMBER=57 THEN MODE:='MFSK16' ELSE

IF NUMBER=60 THEN MODE:='MFSK8' ELSE

 

{"RTTYM" parameter 1 parameter 2 (parameter 1: "4" (4 tones),  "8" (8 tones), "16" (16 tones), "32" (32 tones), parameter 2: "250" (B=250 Hz), "500" (B=500 Hz) or "1000" (B=1000 Hz))...same parameters as OLIVIA

Examples: RTTYM-32-1000 or RTTYM-8-500

Note: the following are the main RTTYM modes: RTTYM-4-250, RTTYM-4-500, RTTYM-8-250, RTTYM-8-500, RTTYM-16-500, RTTYM-16-1000, RTTYM-32-1000}

IF NUMBER=61 THEN MODE:='RTTYM-8-250' ELSE

IF NUMBER=62 THEN MODE:='RTTYM-16-500' ELSE

IF NUMBER=63 THEN MODE:='RTTYM-32-1000' ELSE

IF NUMBER=65 THEN MODE:='RTTYM-8-500' ELSE

IF NUMBER=66 THEN MODE:='RTTYM-16-1000' ELSE

IF NUMBER=67 THEN MODE:='RTTYM-4-500' ELSE

IF NUMBER=68 THEN MODE:='RTTYM-4-250' ELSE

 

{"OLIVIA" parameter 1 parameter 2 (parameter 1: "4" (4 tones),  "8" (8 tones), "16" (16 tones), "32" (32 tones), parameter 2: "250" (B=250 Hz), "500" (B=500 Hz) or "1000" (B=1000 Hz))

Examples: OLIVIA-32-1000 or OLIVIA-8-500

Note: the following are the main Olivia modes: OLIVIA-4-250, OLIVIA-4-500, OLIVIA-8-250, OLIVIA-8-500, OLIVIA-16-500, OLIVIA-16-1000, OLIVIA-32-1000}

IF NUMBER=69 THEN MODE:='OLIVIA-8-250' ELSE

IF NUMBER=70 THEN MODE:='OLIVIA-16-500' ELSE

IF NUMBER=71 THEN MODE:='OLIVIA-32-1000' ELSE

IF NUMBER=72 THEN MODE:='OLIVIA-8-500' ELSE

IF NUMBER=73 THEN MODE:='OLIVIA-16-1000' ELSE

IF NUMBER=74 THEN MODE:='OLIVIA-4-500' ELSE

IF NUMBER=75 THEN MODE:='OLIVIA-4-250' ELSE

 

IF NUMBER=76 THEN MODE:='PAX' ELSE

IF NUMBER=77 THEN MODE:='PAX2' ELSE

IF NUMBER=78 THEN MODE:='DOMINOF' ELSE

IF NUMBER=79 THEN MODE:='FAX' ELSE

{the sub-modes SSTV are automatically recognized in SSTV so no parameters are needed for SSTV}

IF NUMBER=81 THEN MODE:='SSTV' ELSE

 

{"DOMINOEX" parameter 1 and optionally parameter 2 (parameter 1: "4" (4 baud) , "5" (5 bauds),

  "8" (8 bauds), "11" (11 bauds), "16" (16 bauds), "22" (22 bauds),

  parameter 2 "" (no parameter 2 for non-FEC) or "FEC" (for FEC correction))

Example: DOMINOEX-11 or DOMINOEX-16-FEC (parameter 2 is optional)}

IF NUMBER=84 THEN MODE:='DOMINOEX-4' ELSE

IF NUMBER=85 THEN MODE:='DOMINOEX-5' ELSE

IF NUMBER=86 THEN MODE:='DOMINOEX-8' ELSE

IF NUMBER=87 THEN MODE:='DOMINOEX-11' ELSE

IF NUMBER=88 THEN MODE:='DOMINOEX-16' ELSE

IF NUMBER=90 THEN MODE:='DOMINOEX-22' ELSE

IF NUMBER=92 THEN MODE:='DOMINOEX-4-FEC' ELSE

IF NUMBER=93 THEN MODE:='DOMINOEX-5-FEC' ELSE

IF NUMBER=97 THEN MODE:='DOMINOEX-8-FEC' ELSE

IF NUMBER=98 THEN MODE:='DOMINOEX-11-FEC' ELSE

IF NUMBER=99 THEN MODE:='DOMINOEX-16-FEC' ELSE

IF NUMBER=101 THEN MODE:='DOMINOEX-22-FEC' ELSE

 

IF NUMBER=104 THEN MODE:='FELD HELL' ELSE

IF NUMBER=105 THEN MODE:='PSK HELL' ELSE

IF NUMBER=106 THEN MODE:='HELL 80' ELSE

 

{"FMHELL" parameter 1 (parameter 1: "105" (105 bauds) or "245" (245 bauds)),

Example: FMHELL-245}

IF NUMBER=107 THEN MODE:='FM HELL-105' ELSE

IF NUMBER=108 THEN MODE:='FM HELL-245' ELSE

 

IF NUMBER=110 THEN MODE:='QPSK31' ELSE

 

{"PACKET" parameter 1 (parameter 1: "110" (bauds),Example: PACKET-110}

IF NUMBER=113 THEN MODE:='PACKET-110' ELSE

 

IF NUMBER=114 THEN MODE:='141A' ELSE

 

IF NUMBER=116 THEN MODE:='OLIVIA-8-1000' ELSE

IF NUMBER=117 THEN MODE:='CONTESTIA-8-1000' ELSE

IF NUMBER=119 THEN MODE:='RTTYM-8-1000' ELSE

 

IF NUMBER=123 THEN MODE:='DTMF' ELSE

 

IF NUMBER=125 THEN MODE:='ALE400' ELSE

 

IF NUMBER=126 THEN MODE:='BPSK250' ELSE

IF NUMBER=127 THEN MODE:='QPSK250' ELSE

 

IF NUMBER=131 THEN MODE:='FDMDV' ELSE

 

IF NUMBER=132 THEN MODE:='JT65-A' ELSE

IF NUMBER=134 THEN MODE:='JT65-B' ELSE

IF NUMBER=135 THEN MODE:='JT65-C' ELSE

 

IF NUMBER=136 THEN MODE:='THOR-4' ELSE

IF NUMBER=137 THEN MODE:='THOR-8' ELSE

IF NUMBER=138 THEN MODE:='THOR-16' ELSE

IF NUMBER=139 THEN MODE:='THOR-5' ELSE

IF NUMBER=143 THEN MODE:='THOR-11' ELSE

IF NUMBER=145 THEN MODE:='THOR-22' ELSE

 

IF NUMBER=146 THEN MODE:='THROBX-4' ELSE

 

IF NUMBER=147 THEN MODE:='MFSK32' ELSE

IF NUMBER=148 THEN MODE:='MFSK11' ELSE

IF NUMBER=152 THEN MODE:='MFSK22' ELSE

 

IF NUMBER=153 THEN MODE:='CALL ID' ELSE

 

{"PACKET" parameter 1 (parameter 1: "PSKbauds")}

IF NUMBER=155 THEN MODE:='PACKET-PSK1200' ELSE

IF NUMBER=156 THEN MODE:='PACKET-PSK250' ELSE

IF NUMBER=159 THEN MODE:='PACKET-PSK63' ELSE

 

IF NUMBER=163 THEN MODE:='OLIVIA-8-125' ELSE

IF NUMBER=169 THEN MODE:='CONTESTIA-8-125' ELSE

IF NUMBER=170 THEN MODE:='RTTYM-8-125' ELSE

 

{MIL-STD-188-110A in asynchronous format 8N1 (8 data bits, no parity, 1 stop bit)}

IF NUMBER=172 THEN MODE:='110A-8N1' ELSE

 

IF NUMBER=173 THEN MODE:='BPSK500' ELSE

 

{ "PSK Robust" or "PSKR" in short}

IF NUMBER=183 THEN MODE:='PSK125R' ELSE

IF NUMBER=186 THEN MODE:='PSK250R' ELSE

IF NUMBER=187 THEN MODE:='PSK500R' ELSE

 

{"PACKET" PSK at 31 bauds (parameter 1: "PSKbauds")}

IF NUMBER=189 THEN MODE:='PACKET-PSK31' ELSE

 

{Contestia modes for UHF and emergency communications }

IF NUMBER=191 THEN MODE:='CONTESTIA-64-2000' ELSE

IF NUMBER=193 THEN MODE:='CONTESTIA-64-1000' ELSE

IF NUMBER=194 THEN MODE:='CONTESTIA-64-500' ELSE

IF NUMBER=201 THEN MODE:='CONTESTIA-32-2000' ELSE

 

{additive Olivia and Contestia modes}

IF NUMBER=203 THEN MODE:='OLIVIA-4-125' ELSE

IF NUMBER=204 THEN MODE:='CONTESTIA-4-125' ELSE

IF NUMBER=211 THEN MODE:='OLIVIA-64-2000' ELSE

IF NUMBER=214 THEN MODE:='OLIVIA-8-2000' ELSE

IF NUMBER=221 THEN MODE:='OLIVIA-32-2000' ELSE

IF NUMBER=229 THEN MODE:='OLIVIA-4-1000' ELSE

IF NUMBER=234 THEN MODE:='OLIVIA-16-2000' ELSE

IF NUMBER=238 THEN MODE:='OLIVIA-4-2000' ELSE

IF NUMBER=247 THEN MODE:='CONTESTIA-8-2000' ELSE

IF NUMBER=254 THEN MODE:='CONTESTIA-4-2000' ELSE

IF NUMBER=255 THEN MODE:='CONTESTIA-4-1000' ELSE

IF NUMBER=259 THEN MODE:='CONTESTIA-16-2000' ELSE

IF NUMBER=261 THEN MODE:='CONTESTIA-128-2000' ELSE

 

{mode Lentus}

IF NUMBER=262 THEN MODE:='LENTUS' ELSE

 

{RSID-EOT for “End Of Transmission”, to re-enable a squelch or notify a completion of transfer, for example}

IF NUMBER=263 THEN MODE:='EOT' ELSE //EOT is a pseudo mode here

 

{modes AUTEX}

IF NUMBER=266 THEN MODE:='AUTEX2' ELSE

IF NUMBER=267 THEN MODE:='AUTEX4' ELSE

IF NUMBER=268 THEN MODE:='AUTEX7' ELSE

IF NUMBER=271 THEN MODE:='AUTEX13' ELSE

 

{Extension of RSID, for a two sequences RSID code}

IF NUMBER=6 THEN MODE:='EXTENSION_FLDIGI' ELSE

IF NUMBER=102 THEN MODE:='EXTENSION_FLDIGI' ELSE

IF NUMBER=168 THEN MODE:='EXTENSION_FLDIGI' ELSE

IF NUMBER=174 THEN MODE:='EXTENSION_FLDIGI';

 

73

Patrick

 

 


Re: New digital mode PS-18 (HF pager) from DXsoft and Radial, or we invented APRS again :-)

Sergei Podstrigailo
 

Hello All,

HF Pager for Windows 3.10 is released:

https://www.dxsoft.com/hfpagerw.zip - Newest Windows version
https://www.dxsoft.com/hfpagerw-reg.htm - Windows version purchase

HF Pager for Android 3.33 is released:

https://www.dxsoft.com/hfpagerng.apk - Newest Android NG version
https://www.dxsoft.com/hfpagerdm.apk - Newest Android demo version
https://www.dxsoft.com/hfpagergg.apk - Newest Android Google version
https://www.dxsoft.com/hfpagerng-reg.htm - Android NG version purchase



===

HF Pager for Windows versions history

V3.10
An error in the symbol synchronization algorithm was fixed.
Used baud rate is saved in the text header of sent or received message.
The acknowledge packet (ACK) includes the Error Rate of
the received message, which is then stored in the sent message text header.
V3.02
The bug was fixed - a CW-ID was transmitted not only after a beacon,
but also after a general message.
V3.01
You can now manually set the coordinates used in the beacon when there
is no GPS receiver (or when there is no data from it).

You can now include a CW-ID (up to 16 symbols) in the beacon.

The set of possible beacon transmission periods has been changed.

The waterfall displays the receiving frequencies corresponding to the selected baud
rate, as well as the nominal receiving frequencies for the 1.46 bauds speed.

The weather forecasts received from the HFPgate (V1.60 NG and newer or HFP Weather)
by the "=x..." command are converted to the human-readable form and saved into
the special folder. A separate folder is created for all messages received on
the same day (local or UTC time, dependings on the settings). Therefore, when the
weather request is making around midnight the sequence of received forecasts can be
splitted into two folders.

Minor fixes have been made.
2.92
The click on "=xGPS" or "#(GPS)" button inserts the current
GPS-coordinates into the beginning of the message (in one of the two formats).

A point with the received coordinates can be displayed on the
selected map by the popup menu.
2.91
The minimum preamble length has been increased to three seconds.

The retransmission logic was changed:
If a NAK (error receipt) is received, then a
message is retrassmitted even if
"Resent till not CFM" checkbox is not set.

PTT control options "OmniRig / CAT" and "OmniRig / Com-port pins" were added.

At 23.44 and 46.88 baud rates ACK or NAK are repeated twice
(with single preamble).
[...]

HFpager for Android Versions History

V3.33
An error in the symbol synchronization algorithm was fixed.
Used baud rate is saved in the text header of reseived message
or in the end of sent message text.
The acknowledge packet (ACK) includes the Error Rate of
the received message, which is then stored in the end of sent message text.
V3.31
The program works even if the standard "Documents" folder has been moved
to the external SD-card.
V3.30
The weather forecasts received from the HFPgate (V1.60 NG and newer)
by the "=x..." command are converted to the human-readable form and saved into
the special folder. A separate folder is created for all messages received on
the same day (local time). Therefore, when the weather request is making around
midnight the sequence of received forecasts can be splitted into two folders.
V3.27
The click on "=xGPS" or "#(GPS)" button inserts the current
GPS-coordinates into the beginning of the message (in one of the two formats).
A point with the received coordinates can be displayed on the
selected map or transferred to another application as geo-intent by the popup menu.

During creating a new message by the "Resend message" menu item the
recipient ID of the original message is placed into the "To:" field.

During creating a new message by the "Reply" menu item the
sender ID of the original message is placed into the "To:" field.
The text of the new message remains blank in this case.
V3.26
The explanatory message is shown before requesting access to device location.
V3.25
If the message forwarded from the air to SMS contains "= x"-coordinates,
a link to Google Maps is added to outgoing SMS (in the NG-version).
[...]



--
Best regards,
Sergei mailto:amx2@dxsoft.com

Windows HAM radio software at http://www.dxsoft.com


new SW Radiogram program available

 

Hello to all the digital folks out there.
 
A new program for the Shortwave Radiogram broadcasts has now been posted on the SW Radiogram website.
 
If you're new to decoding digital, this is a pretty nice way to get your feet wet. You can use your desktop or laptop, or you can use an Android device such as a smartphone or tablet. You can find links to the SW Radiogram website, software for decoding, and wiki articles with extensive details and help at: http://www.udxf.nl/events.html.  
 
If you'd like to see a list of web receivers (which are often reported as being used), receiver, transceiver and SDR applications and more, take a look at the SW Radiogram gateway at https://wiki.radioreference.com/index.php/Shortwave_Radiogram_Gateway
 
Help is also available on Facebook and Twitter. The SW Radiogram website has the links. 
 
Radio Northern Europe International also uses digital modes during its broadcasts. The August schedule hasn't been announced as of this writing.  
See https://rnei.org/ for more information. You can also check out Channel 292's RNEI schedule here
https://www.channel292.de/schedule-9670-khz/?fbclid=IwAR3BV3T6a10RJD7BDwE-dYi2ZEJru5u_vAqZEETMrAh2r5AeMi_q3D39peY
 
Here's hoping for good propagation 


Re: Understanding APSK and QAM Rohde and Schwartz video #VARA

Graham
 

Its very wide subject [ no pun  intended]  

from what I can  see, vara  has a  ack  fame  

The introduction  of  dsss  , did  provided the  ability to recover signals from the  noise ,  as part of a  DSP process 

To  spread the  signal over the  pass  band requires  additional  padding  data   , this  is  derived  from the direct  sequence  random  number
generator , hence the  dsss  name tag  , just moving the  signal round the  pass  band ,  will  not  produce ''gain''  olivia ,  chip64 and ROS HF all  use 
dsss  to  provide the  additional  data , enabling  spreading  gain  , ie high level of  redundancy - first  gen  1G, the  difference  being  chip64 , based on FM  used the  side bands ,  chips , inside a  2.4 K ssb channel ,  to spread the  data  across  the  b/w ,  where as  olivia  and  Ros  are  mfsk ,  so its the  modem that  places the  carriers , all  these  systems  provide  below the  noise  function  

The adding of the  cdma layer to the  MFSK modem , then  provides  access  to the  unused  spectrum  ,  rather than  double  coding , its a  two  stage  process  ,{ DSP + Dsss  }  then  + cdma  , see  the  attached  power point  presentation , this is the  basis of the  2G mobile  phone system ,  Higher  levels  G,3,4,5  are not  possible  on H due to the  extreme b/w  requirements , It  was an   interesting  observation, that the  MF modes  Ros  designed , did not  use  dsss , being  narrow band 90 Hz  , coupled with the  stability of the  MF band ,  no  phase issues  etc. then  mfsk  provided the  required  solution , again the  first  frame  is a lock frame , there being  no limit to the  text  length , a stop frame is  provided to  revert the  rx to  standby  at the  end of the  'over'  

Your right,  digital processing is  not  something  covered , Its important to  recognise ,  some popular concepts and   regulations  in this  area  are based  on pioneering  work  undertaken at the  time , which  , has been  superseded ,

eg , 'spread spectrum'  is not  actually  based on  bandwidth , but  very few, will  agree  with that  -)

73-Graham 
g0nbd 
 
This is one of the  established  works on the  subject ,  but  for  me , makes  heavy reading  



Re: Understanding APSK and QAM Rohde and Schwartz video #VARA

Kristoff Bonne
 

Graham,


I'm sorry but this is all a bit confusing.


DSSS is not at all related to pulling a signal out of the background noise.

- Just like Chirp spread-spectrum, it can be used to deal with interference of other signals or to distribute multiple signals over the same frequency-range, but that  cannot help to remove random background -noise (*) that we are dealing with here. So that does not apply here.

- And yes, it is also used to create an additional layer of noise to obfuscate a message, but that is not related to amateur-radio neither.


Also, a 'burst' as a data-payload makes even less sense, as that is a OSI layer-2 concept, while we are dealing with a OSI layer-1 question here.




For some reason, the amateur-radio community has always had it difficult to understand the basic ideas of SDR, DSP and digital communication, mainly because there have  few people teaching it in the ham-radio classes, in a simple structured way. What is needed is a learning-path that breaks down this subject in an easy to digest parts so that people can start building up knowledge step by step.

Having all kind of (unrelated) words, terms and abbreviations all thrown together does not really help.




The question remains:

If VARA does not need an external reference when a signal (it does not see) starts, how does it manage to pull a bits out a signal-stream (e.g. when the signal is 23 db below the noise-floor).




73
kristoff - on1arf

(*) https://pysdr.org/content/noise.html#awgn

On 20.08.21 15:58, Graham wrote:
On Fri, Aug 20, 2021 at 07:16 AM, Kristoff Bonne wrote:

burst

Hi Kristoff

contrast  and compare


May  be  on   different  subjects , Burst , detectable Sigle shot ....something  in or  under the  noise ,  would be  classically defines as  ' low  probability  of intercept ' ie hidden , not explicitly linked to   ham radio ,but the  techniques , are linked  , eg Olivia  , can  function  under the  noise floor , but in terms of  efficient  use of bandwidth , as in number  of qso's / KHz   , its  limited to   only  '1'  , 2 Khz  occupied b/w  =   1 qso , Olivia  is   1 G  system  as  is  Chip-64  +++

ROS HF is  2 G   below the  noise  system, where  using   a combination  of  DSSS  and  CDMA ,  multiple  simultaneous access  to the  same  2KHz is  made possible , with the  same s/n  ,

Text books indicate the  dsss  coding  is  applied to the  data pay load and the  cdma  to  the  modem  , it was and  remains a significant  milestone  for  Ham coms , but ,  the  highest users  remain the  27 MHz  CB  , as  can be  observed  from the psk-map , where  , the mode provides a  ''jump in and  chat'' environment , just as  2g mobile  phones  , did  for  text


Burst ,  Classically that  referred to   military  com's where  a  single  'radio  burst'  contained the  data  pay load ,  the single  shot, making detection  and   RDF difficult**  ...  there had to  be  assumption that the  burst was  received  and  decoded ,
*** With  DSP  SDR    etc , this  is no longer  valid ,  moving to  under the  noise  and/or  wide  spectrum  use

As to the  make  up of the  'burst ,  its possible a  single pulse could be  so  construed ,  as in ,  its detection  signifies  a change  of status   0>1

 A  single  packet frame could be  a burst , with  conventional start -data - stop format , but  quite fragile as  , no fec and needs 100% copy of each bit, error = repeat = no longer burst   , as simple rtty  or  as can be  seen ,  with a  fixed payload length , coding  can  encapsulate the  data , then  requiring  , the  minimum recovery of  ~ 40% or more to  recover the  pay load ..opera beacon  250 bits ,  opera qso  15 chrs plain text  450 bits  , both  have min 40% recovery  ,  opera used 1 carrier ,  to provided  data  from  CW  Tx , found  on the  LF bands  of there time , other wise  its a  really  silly  concept , but has found various  uses  -)

PSK ,  Yes  functioned  quite well , but limited  in  phase fragility and  efficiency ,  in contrast to  mmfsk

Part of the  original  ROS  data  mode's  are the  MF  narrow b/w MFSK   modes  MF-2  and  MF-7
MF-7  provides  a  similar data  rate , live  key board , qso  mode  to  PSK-31 ,  at  ~ -10 dB lower
DSP + mfsk utilising  single  tones  = maximum  efficiency

RTTY  remains  a  contest  mode ,  not  having  fec ,  its  a what  you  see is what  you  get  mode
if  you  capture the  ''word''   start xxxxx stop  , then you have the  chr  , no  processing  time
but you  do need  to  capture  100% , if you  miss the  shift , you  can  guess ,
ryryry  is 64646...etc

73-Graham
g0nbd

+++  NB As the  number of data  users  increase  and the  HF propagation  conditions  improve , the  deployment of  single access  systems  ,  will  see large  sections of the  bands engulfed , as  users  spread out  along the dial  looking for empty b/w
already  in progress  now ...

*.in contrast the  entire  world  of  CB  uses only  1 channel  for  ROS HF and have  so  for  nearly a  decade ... *



Re: Understanding APSK and QAM Rohde and Schwartz video #VARA

Graham
 

On Fri, Aug 20, 2021 at 07:16 AM, Kristoff Bonne wrote:
burst
Hi Kristoff 

contrast  and compare  


May  be  on   different  subjects , Burst , detectable Sigle shot  ....something  in or  under the  noise ,  would be  classically  defines as  ' low  probability  of intercept ' ie hidden , not explicitly linked to   ham radio ,but the  techniques , are  linked  , eg Olivia  , can  function  under the  noise floor ,  but in terms of  efficient  use of bandwidth , as in number  of  qso's / KHz   , its  limited to   only  '1'  , 2 Khz  occupied  b/w  =   1 qso , Olivia  is   1 G  system  as  is  Chip-64  +++

ROS HF is  2 G   below the  noise  system, where  using   a  combination  of  DSSS  and  CDMA ,  multiple  simultaneous  access  to the  same  2KHz is  made possible , with the  same  s/n  ,

Text books indicate the  dsss  coding  is  applied to the  data  pay load and the  cdma  to  the  modem  , it was and  remains a  significant  milestone  for  Ham coms , but ,  the  highest  users  remain the  27 MHz  CB  , as  can be  observed  from the  psk-map , where  , the mode provides a  ''jump in and  chat'' environment , just as  2g mobile  phones  , did  for  text 


Burst ,  Classically that  referred to   military  com's where   a  single  'radio  burst'  contained the  data  pay load ,  the  single  shot, making detection  and   RDF difficult**  ...  there  had to  be  assumption that the  burst was  received  and  decoded ,
*** With  DSP  SDR    etc , this  is no longer  valid ,  moving to  under the  noise  and/or  wide  spectrum  use 

As to the  make  up of the  'burst ,  its possible a  single pulse could be  so  construed ,  as in ,  its detection  signifies  a change  of status   0>1

 A  single  packet frame could be  a burst , with  conventional  start -data - stop format , but  quite fragile as  , no fec and needs 100% copy of each bit, error = repeat = no longer burst   , as simple rtty  or  as can be  seen ,  with a  fixed payload length , coding  can  encapsulate the  data , then  requiring  , the  minimum recovery of  ~ 40% or more to  recover the  pay load ..opera beacon  250 bits ,  opera qso  15 chrs plain text  450  bits  , both  have min 40% recovery  ,  opera used 1 carrier ,  to provided  data  from  CW  Tx , found  on the  LF bands  of there  time , other wise  its a  really  silly  concept , but has found  various  uses  -)

PSK ,  Yes  functioned  quite well , but limited  in  phase  fragility and  efficiency ,  in contrast to  mmfsk 

Part of the  original  ROS  data  mode's  are the  MF  narrow b/w  MFSK   modes  MF-2  and  MF-7
MF-7  provides  a  similar data  rate , live  key board , qso   mode  to  PSK-31 ,  at  ~ -10 dB lower
DSP + mfsk utilising  single  tones  = maximum  efficiency 

RTTY  remains  a  contest  mode ,  not  having  fec ,  its  a what  you  see is what  you  get  mode
if  you  capture the  ''word''   start xxxxx stop  , then you  have the  chr  , no  processing  time 
but you  do need  to  capture  100% , if you  miss the  shift ,  you  can  guess , 
ryryry  is 64646...etc 

73-Graham
g0nbd

+++  NB As the  number of data  users  increase  and the  HF propagation  conditions  improve , the  deployment of  single  access  systems  ,  will  see large  sections of the  bands  engulfed , as  users  spread out  along the dial  looking for  empty b/w  
already  in progress  now ...

.in contrast the  entire  world  of  CB  uses only  1 channel  for  ROS HF and have  so  for  nearly a  decade ...  



Re: Understanding APSK and QAM Rohde and Schwartz video #VARA

Kristoff Bonne
 

Hi Graham,


Thanks for the very long reply.

Two points:

But there is something I do not understand:
You have mentioned 'burst' a couple of times, but -whatever it may be- if it inside the noise, the receiver will simply not detect it so I do not see how it can help in this.
(It is not because something has a different name, that the law of physics  do not apply, is it?)


For the people who are interested in this, I am thinking of creating a small GR GRC-file for this to explain who one can pull a signal out of the noise by "averaging away the noise".



Concerning PSK31, I may be wrong, but I think it was one of the first modes after RTTY that was easy to use and allowed quick and easy two-way QSOs, which is what is needed for contesting. So, considering the time-frame, I do not think we should be to harsh on them :-)

What is a bit strange is that it uses a completely different pulse-shaping filter then most all others. Here is an interesting article about it:
https://ham.stackexchange.com/questions/7703/filtering-for-psk31-demodulation.

It would be nice experiment to create two psk31 signals, one with a RC and the other with a RRC, next to each other and see if it actually makes any difference in real live usage.

For who is interested, more info on pulse-shaping filters:
https://pysdr.org/content/pulse_shaping.html



73
kristoff - on1arf

On 19.08.21 00:38, Graham wrote:
Hi Kristoff

Thread is  a  little  wide to , pick up all the  points

amazed ,  no live  psk on the  bands ,  must admit ,  it was never too  robust , worked nicely  on the  higher  bands , where not too  much  'turbulence  , especially   10 meters

//OFDM systems are good at dealing with where where interference at one very precise specific frequency.//

Possibly not so, this is a ofdm signal ,[was a image ?] showing selective fade , a high % of the signal escapes the attenuation , the out come being, the system continues to function , ie its very capable of dealing with noise distributed in the channel , in terms of time and spectrum , only needs to capture ' bits / patches of the transmission , to recover the pay-load .. /But for that, it must have a rough idea when the bits start./
/That's why systems like very narrow-band modes (WSPR and similar) use an external time-reference (i.e. the clock of the PC) to determine when it must start receiving. /Not so , opera is a free running system, with no time locking required , once the data bits are recovered , the sync is then extracted ..noting opera is packet like system where the data frame is fixed length and the payload is also fixed length ,
the coding encapsulates the payload , and not having to provide a open ended , non time limited decode , there is no start or finish , only the need to capture 40 + % this requires a high redundancy level , noting the deep search [ correlation] second chance detector provided for 477&136 KHz , retains the 40+% min capture criteria , as well as the AFC , making it very robust and independent of equipment stability

Other  low s/n  modes , require to  establish   ''lock'  before the  decoding can  commence , the  two  tone start to olivia , or the  ROS  pre-amble , the  delay to  print is  the  FEC time , The ROS-MF  modes  have a  much longer  FEC time to  over come the QSB found  on  MF , ROS-HF much  shorter , as Opera   op8  bridges the  slow  qsb  MF , Op32  30 mins  , works  well  on 136  where  fade  times  are  very long ,  each  retains the  40 + %  requirement

Opera  could be  categorised  as  a  data  burst  system  , perhaps  not  so [much ?]  packet , as that  requires the conventional  start - data- stop  format , but  still  a single burst ,  could be  received ..

wspr uses time frame , as the coding is very low level , make use of correlation , to provide low s/n , correlation is normally used to recover the data bits from the RX stream , going for large blocks , requires accurate time matching , this  couple  with  multiple  passes , where the  signal is repeated , verbatim, slowly  recovers the  signal [ may be 2 dB per pass] , not having  handled the  detection  in DSP , this limited  in terms of  AFC -  has none ,  It responds to tones  +/- of the  selected  qrg,  to  provide  drift accommodation , the down side being   strong  carriers , desensitise  the  system  , also   requires  high % recovery to  function ..

Its a  detection  system ,  it detects  signals ,  that  was its original  function, the  issue's  occur  when , comparisons  are made with  free  running  data  modes , one  repeating  issue  is the  50% duty cycle  of  opera ,  to deliver the  same  energy as  wspr-2 ,, opera needs to  run for  x2  the  time , however  as the  coding  efficiency is  very high   op2 and wspr2  have similar s/n ratings , with  only  half the  supplied  energy and single  pass ,

APSK and QAM  , I don't have the  proof ,  only  point to  the concept  being  used  ,  I assume  provides the  maximum  pay load for  the  minimum  bandwidth  , the orthogonal aspect ,  is linked to  carrier  stacking in the  B/W , as not to  interfere with each  other   .. being FM , the  side bands  are  exact replicas of the  main and extend  -/+ , where  in mfsk , the  tones  are placed  by the modem pattern  generator ,  each  only  occupying a  single  frequency , being  left to the  dsp to  determine where  and what  fills the  pass  band

73-Graham









new SW Radiogram program available

 

Hello to all the digital folks out there.
 
A new program for the Shortwave Radiogram broadcasts has now been posted on the SW Radiogram website.
 
If you're new to decoding digital, this is a pretty nice way to get your feet wet. You can use your desktop or laptop, or you can use an Android device such as a smartphone or tablet. You can find links to the SW Radiogram website, software for decoding, and wiki articles with extensive details and help at: http://www.udxf.nl/events.html.  
 
If you'd like to see a list of web receivers (which are often reported as being used), receiver, transceiver and SDR applications and more, take a look at the SW Radiogram gateway at https://wiki.radioreference.com/index.php/Shortwave_Radiogram_Gateway
 
Help is also available on Facebook and Twitter. The SW Radiogram website has the links. 
 
Radio Northern Europe International also uses digital modes during its broadcasts. The August schedule hasn't been announced as of this writing.  See https://rnei.org/ for more information.
   
Here's hoping for good propagation 


Re: Understanding APSK and QAM Rohde and Schwartz video #VARA

Graham
 

Hi Kristoff 

Thread is  a  little  wide to , pick up all the  points 

amazed ,  no live  psk on the  bands ,  must admit ,  it was  never too  robust , worked nicely  on the  higher  bands , where not too  much  'turbulence  , especially   10 meters  

/OFDM systems are good at dealing with where where interference at one very precise specific frequency./

Possibly not so, this is a ofdm signal ,[was a image ?] showing selective fade , a high % of the signal escapes the attenuation , the out come being, the system continues to function , ie its very capable of dealing with noise distributed in the channel , in terms of time and spectrum , only needs to capture ' bits / patches of the transmission , to recover the pay-load ..

But for that, it must have a rough idea when the bits start.
That's why systems like very narrow-band modes (WSPR and similar) use an external time-reference (i.e. the clock of the PC) to determine when it must start receiving.

Not so , opera is a free running system, with no time locking required , once the data bits are recovered , the sync is then extracted ..noting opera is packet like system where the data frame is fixed length and the payload is also fixed length ,
the coding encapsulates the payload , and not having to provide a open ended , non time limited decode , there is no start or finish ,

only the need to capture 40 + % this requires a high redundancy level , noting the deep search [ correlation] second chance detector provided for 477&136 KHz , retains the 40+% min capture criteria , as well as the AFC , making it very robust and independent of equipment stability


Other  low s/n  modes , require to  establish   ''lock'  before the  decoding can  commence , the  two  tone start to olivia , or  the  ROS  pre-amble , the  delay to  print is  the  FEC time , The ROS-MF  modes  have a  much longer  FEC time to  over come the  QSB found  on  MF , ROS-HF much  shorter , as Opera   op8   bridges the  slow  qsb  MF , Op32  30 mins  , works  well  on 136  where  fade  times  are  very long ,  each  retains the  40 + %  requirement 

Opera  could be  categorised  as  a  data  burst  system  , perhaps  not  so [much ?]  packet , as that  requires the  conventional  start - data- stop  format , but  still  a single  burst ,  could be  received .. 

wspr uses time frame , as the coding is very low level , make use of correlation , to provide low s/n , correlation is normally used to recover the data bits from the RX stream , going for large blocks , requires accurate time matching ,
this  couple  with  multiple  passes , where the  signal is  repeated , verbatim, slowly  recovers the  signal [ may be 2 dB per pass] , not having  handled the  detection  in DSP , this  limited  in terms of  AFC -  has none ,  It responds to tones  +/- of the  selected  qrg,  to  provide  drift accommodation , the  down side being   strong  carriers , desensitise  the  system  , also   requires  high % recovery to  function .. 

Its a  detection  system ,  it detects  signals ,  that  was its  original  function, the  issue's  occur  when , comparisons  are made with  free  running  data  modes , one  repeating  issue  is the  50% duty cycle  of  opera ,  to deliver the  same  energy  as  wspr-2 ,, opera needs to  run for  x2  the  time , however  as the  coding  efficiency is  very high   op2 and wspr2  have  similar s/n ratings , with  only  half the  supplied  energy and  single  pass , 

APSK and QAM  , I don't have the  proof ,  only  point to  the  concept  being  used  ,  I assume  provides the  maximum  pay load for  the  minimum  bandwidth  , the orthogonal aspect ,  is linked to  carrier  stacking in the  B/W , as not to  interfere with  each  other   .. being FM , the  side bands  are  exact replicas  of the  main and extend  -/+ , where  in mfsk , the  tones  are  placed  by the modem pattern  generator ,  each  only  occupying  a  single  frequency , being  left to the  dsp to  determine where  and what  fills the  pass  band 

73-Graham 









Re: Understanding APSK and QAM Rohde and Schwartz video #VARA

Kristoff Bonne
 

Hi Graham,


OK, with a couple of days of delay,  some more quick replies.

(inline reply)


On 10.08.21 22:43, Graham wrote:
kristoff I guess that was the  main idea of the  video. just demonstrating , the  summation of differing modulations, to provide the  maximum  loading , of a single  carrier ,
From there on, things take on there  own  'life' many points ..
Well, this still leaves me with the question I started with.

Concerning APSK and QAM, in the video there  was an example of a system that used a constellation that was a mix of both AFSK and QAM.
I still do not understand  what would be the technical advantage of such a system.

Or, it must be that the advantage isn't technical at all. Perhaps they just want to have something that is different from was has been used before so they can patent it.

Kind of remind me of LoRa. That also has certain things in -to me-  just seams "a little but different from any other system". I guess they needed something so they could patent it and sell their chips.


Note, if you are interested. there is an interesting talk from CCC 2016 by Matt Knight who did the first work to reverse-engineer the LoRa PHY:
https://media.ccc.de/v/33c3-7945-decoding_the_lora_phy

The information is a bit outdated (e.g. the whitening-sequence for the header has now also been found), but it is still quite interesting. It's an interesting use-case of using spread-spectrum to deal with interference in a very saturated piece of radio-spectrum.



The reference's to Shannon sometimes run wide of the  mark, from what I can gather , the  limit  applies to a  fixed set of  parameters , at a fixed time, where as in a live  path, parameters change , so to  quote a  system reaches  etc, when the  path  changes the  parameters is  misleading ..
As I see it, Shannon's theorem is what it is. It determines the theoretical maximum bitrate for a certain S/N at a certain point in time over a certain bandwidth.
If your radio-channel has zones with different levels of noise, or if the S/N changes in time, you need to calculate it per frequency/time slot and add it all together.


Chapters 7 and 10 of the excellent 'pysdr' website by Marc Lichtman explain it quite good:
https://pysdr.org/content/noise.html
https://pysdr.org/content/channel_coding.html

(I advice that website to everybody who starts out learning about SDR and DSP. It's a very good intro in the topic, without all the math; that next to the famous "software defined radio with the HackRF" video-series by Michael Ossmann)


(cut)


with out knowing the  coding , compression and  expansion , its difficult to actual  measure anything , yes  first use  of  MT63  , the original  ofdm  data  mode ,  cw could be  seen  inside the  pass band,  not  affecting the  qso , olivia later gave  much lower s/n ,  probably the  first ham  under the  noise  mode ..
Well, the video on LoRa did get me thinking about these 'below noise' modes.

As said, LoRa is a great mode to operate in saturated radio-spectrum. What is does is by 'encoding' the information not just in a carrier at a specific frequency, but in a signal with a continuously changing frequency (the 'chirp'), it manages to avoid that the interfering-signal correlated to the wanted signal; effectively largely reducing the impact of the interference on the signal.

MT-systems do in essence the same thing.
By encoding the information in multiple changing frequencies, it breaks the correlation between the wanted signal and the interference.

Thinking about it, other frequency-hopping modes do the same thing.


this  at first glance looks like a  simple  ,250 bit  serial  data  stream
but actually  not, its  burst  packet system,  ...
What exactly is a burst packet system?


with very high level of coding  and  efficiency
OK, but coding, error-correction, e.a. are OSI layer-2 capabilities, so strictly speaking not related to the layer-1 features.


Rx decoding , requires the  capture  of  a minimum of 40% of the  transmitted data
this capture  may be  randomly . in blocks ,  at the  start , middle  or at the  end of the  Time line
Well, this is a bit strange.


In essence, you cannot have a below-noise system that can start decoding a signal at any time. By its nature, it cannot detect the synchronization-patterns so can't even determine when the signal begins.

A below-noise system does not have 'real-time' access to the signal it receive as -as the name says-  the signal is buried below the noise-floor.
It's only after taking in a large portion of the stream and taking the average of every frequency-bin (over time, from bit-boundary to bit-boundary) it can detect the presence of the bit. But for that, it must have a rough idea when the bits start.
That's why systems like very narrow-band modes (WSPR and similar) use an external time-reference (i.e. the clock of the PC) to determine when it must start receiving.


sync is  provided by Manchester  coding , so each recovered  bit is  self-sync
Hum .. Manchester-decoding is done after you have retrieved your bits. It cannot help to extract the bits out of the noise.



/OFDM systems are good at dealing with where where interference at one very precise specific frequency./ Possibly not so, this is a ofdm signal , showing selective fade , a high % of the signal escapes the attenuation , the out come being, the system continues to function ,

Euh, . wasn't that what I said?



73-Graham
------------------------------------------------------------------------
Recommended general digital mode software : Multipsk, Fldigi, Winwarbler ( DXLab Suite)
PSK31 calling frequencies = 17M 18103 USB (dial) PLUS 1000Hz center frequency

Small side-question:

Does you know frequencies where there is still a lot of PSK31 activity?

I am working on a PSK demodulator in GNU Radio and would like to try out a PSK31 demodulator.
But it's pretty difficult to find a good source for 'live' signals.

(I know, I can always create them myself with fldigi)



73
kristoff - ON1ARF


new SW Radiogram program available

 

Hello to all the digital folks out there.
 
A new program for the Shortwave Radiogram broadcasts has now been posted on the SW Radiogram website. Note that a new mode is being tested, and
requires the installation of a new version of FLDigi if you wish to receive the data. See the SW Radiogram website for more information.
 
If you're new to decoding digital, this is a pretty nice way to get your feet wet. You can use your desktop or laptop, or you can use an Android device such as a smartphone or tablet. You can find links to the SW Radiogram website, software for decoding, and wiki articles with extensive details and help at: http://www.udxf.nl/events.html.  
 
If you'd like to see a list of web receivers (which are often reported as being used), receiver, transceiver and SDR applications and more, take a look at the SW Radiogram gateway at https://wiki.radioreference.com/index.php/Shortwave_Radiogram_Gateway
 
Help is also available on Facebook and Twitter. The SW Radiogram website has the links. 
 
Radio Northern Europe International also uses digital modes during its broadcasts. The August schedule hasn't been announced as of this writing.  See https://rnei.org/ for more information.
   
Here's hoping for good propagation 


Re: Understanding APSK and QAM Rohde and Schwartz video #VARA

Graham
 

kristoff

I guess that was the  main idea of the  video. just  demonstrating , the  summation of differing modulations, to  provide the  maximum  loading , of a single  carrier ,  

From there on, things take on there  own  'life' many points ..

The reference's to  Shannon sometimes run wide of the  mark, from what I can gather , the  limit  applies to a  fixed set of  parameters , at a fixed time, where as in a live  path, parameters change , so to  quote a  system reaches  etc, when the  path  changes the  parameters  is  misleading ..

Drm ,  you  can spend hours watching the set of  lights ,  never quire  reach the  top , for  lock ,  used to be  BBC had  test MW station  and  Luxembourg  1440 , which gave a  good  copy,  all  now appear to of stopped , but I note  VK  & USA  ? is  now  running  DRM .. Its not  classic odfm , as the  signal is  structured with  central  core , probably in an  attempt to  make it  more robust .. the idea being, the  core  will  get through ..

with out knowing the  coding , compression and  expansion , its difficult to  actual  measure anything , yes  first use  of  MT63  , the  original  ofdm  data  mode ,  cw could be  seen  inside the  pass  band,  not  affecting the  qso , olivia later gave  much lower s/n ,  probably the  first ham  under the  noise  mode ..

with out knowing , what each frame  conveys , its difficult to  speculate  exactly  , what is being  spread over the  vara ofdm carrier group , or  as to what is relayed  along the  time line  

Take for  example the  Opera data  system . 

this  at first  glance looks like a  simple  ,250 bit  serial  data  stream 
but actually  not, its  burst  packet system,  with very high level of coding  and  efficiency 
Rx decoding ,  requires the  capture  of  a minimum of 40% of the  transmitted  data 
this capture  may be  randomly . in blocks ,  at the  start ,  middle  or at the  end of the  Time line 
sync is  provided by Manchester  coding , so each recovered  bit is  self-sync 
thus it's  very  robust , and being  single tone ,  is  immune to  doppler  spread 
s/n is  dependant on energy  , so simply the  time  line is  extended to  gain  -s/n 
uniquely  it provides a  indication  of the  recovered  data , which  in turn  indicates
the  path  quality , in this case only 1 %  data  was lost, virtually  no  need  for FEC ie simple rtty would be ok 
higher % loss = requirement for  more coding  levels , to combat the  loss / time  line 
[something to  try at the  club  for  uhf etc , the  30 second  mode  is provided for  vhf and up to uWave]

19:40 477 IK1HGI Op8 1487.3 Hz -33 dB |------------------------------ ----------------------------------------------------------------------------------------| Fade: 1%


Of note , now,   the  low [mfsk] range  of  the  VARA mode, is  working at lower  levels than the  olivia mode ,  the mfsk modem proved to be  viable  in the  higher  latitudes , where  various disturbances ,  cause the  signal to be  spread, phase changes , echo . the mfsk modem proved  capable of maintaining  link in these  conditions 

OFDM systems are good at dealing with where where interference at one very precise specific frequency.

Possibly not so, this is a ofdm signal , showing selective fade , a high % of the signal escapes the attenuation , the out come
being, the system continues to function ,

In a simple test , the vara modem continued to function in 50% of the required b/w
equivalent to 50% of the b/w being jammed ...note the waterfall display is for indication only ,
and is not linked to the decode process ..so again, difficult to make direct comparisons ..

73-Graham









Re: Understanding APSK and QAM Rohde and Schwartz video #VARA

Kristoff Bonne
 

Hi Graham,


Thank you for your very long reply.


OK. Let's see if I understand this correctly.

On 10.08.21 12:52, Graham wrote:
On Mon, Aug 9, 2021 at 08:13 PM, Kristoff Bonne wrote:

use a combination of QAM and APSK constelation

Kristoff

Its never immediately  obvious , from the  video,  the  issues round  the  pk-pk  levels of the  vara  modem are  perhaps , a little more  translucent  [as opposed to  transparent ] as are the  various  displays ..
So, if I understand this correctly, the goal of the videos is just to show the principle that multi-order PSK and PSK+AM based modulation-schemes (APSK or QAM) can cram more bits into one symbol.

Correct?


The hybrid ...
What exactly do you mean by hybrid?
A hybrid AM/PSK scheme (like APSK and QAM), or a hybrid of APSK and QAM constellations (like the one used by MIL-STD-188-110D, as shown in the end of the video)?


serves to  maximise the  pay load of a  single  carrier ,  perhaps more  fragile, but ,  that's  linked to  the rate ,  the  faster , with the  same energy , then the  higher  becomes the  errors , either  reduce the  rate ,  more  energy/time ..or  increase the  energy , again more  energy , just the  rate of supply  increases ..
OK, this is understand.

I guess is the Shannon-Hartley theorem on the capacity of a radio-channel which links the maximum bitrate to the S/N ratio.



So, is the  issue with  single  high  speed  carriers ,  quite  incompatible with turbulent  conditions  encountered  on HF
one  single  jamming  signal in the  pass band
and everything stops
OK, but this is common to any radio-channel. If the interference fills up a complete channel, there is not much you can do about it.

The only way around that is by using some kind of 'spread-spectrum' technique to distribute your bits over a wide piece of spectrum, or that distributes it in a very specific order (chirp, PRN-based CDMA) to avoid having a correlation between the interference and the wanted signal.

Lora is a very nice example of that. We have been playing around with aprs-over-lora (on 433.775 MHz) in our local radioclub here, and I must say that we really have been  very impressed how well it works in a pretty congested piece of spectrum like the 433 MHz ISM band.


,higher rates fall  over due to  delays and  multi path  etc ..
I do understand that multipath limit the baudrate of a carrier (as delayed copies of an earlier symbols might interfere with the current symbol) but I never understood why delay should be a limiting factor of a simplex radio-channel.



then comes the maximum  rate  compatible with HF ,
Its reasonable , to  take a  guide from the  vara  modem , the maximum rate for  HF is nearly  x10 slower than the  300 baud limit , quoted as  a limiting  factor  , 300 providing a b/w limitation  , for  single  carrier  systems ,  under ideal conditions ,  anything and  everything  works , \

DRM broadcast requires , direct or  single  hop  , anything  after ,  then  it fails to  'lock'
[ as the  sun spot cycle  progresses , the  opportunity for multiple hop connections will  increase]
Well, there aren't that much DRM broadcasts on HF anymore, but I did once manage to receive DRM broadcasts from AIR directly from India to Europe. I am not sure if this was single-hop.



B/W utilisation , Much the  same as  say a   Tank with  tracks , and multiple wheeled  vehicle ,/one track  off ,  stops/, one  tyre  off  , keeps  going ..

Taking the vara   modem has the  optimum   single  carrier  rate for  HF ,

Then ,  as can be seen,  in the  OFDM  levels,  multiple  low rate  carriers   , are  combined , to  provide ,  maximum  rate, maximum  ''in channel ''  jamming /  qrm rejection , where as the on-air  carrier spectrum's  are   provided with  16 ? fixed patterns ,
not  seen, in the coding  of the  modem is the  mathematical  'engine' that seeks to  distribute the  payload  , making  best  use the  the available  channel b/w  and recover it post demodulation .
OK, I am not an expert in VARA (is the source-code available somewhere?) but most data-comm systems I know use a interleaving to distribute the bits (and therefor the biterrors) around in the bitstream so that the Error-correction mechanism can better deal with it.
(Error-mechanisms have difficulties to deal with errors that are close together)

I remember, years ago, having a QSO in olivia when somebody started doing PSK31 smack in the middle of our channel. The interesting thing was, the system had absolutely no issue with that as it only affected one single carrier of the OLIVIA comb and our QSO was still completely 100 % error-free.
That is the power of spread-spectrum techniques, interleaving and FEC, I guess!



.selective  qsb can  remove  sections the  b/w, but  as long as the  minimum criteria is met , for the  recovered  data , the  pay-load can be extracted   if not ,  a more  robust  level  can be  selected , or vice versa
The way I see it is like this.

Take this scenario:
- you receive a the signal that is 3 db over the minimal S/N ratio required to demodulate the signal.
- Two systems:
a/ a single-carrier system taking up the complete bandwidth of a channel
b/ a OFDM system where the bits are distributed over a comb of 8 carriers. (each taking up 1/8 of the bandwidth of a channel).

1/ Image selective qsb that reduces the signal-level of 1/8th of the bandwidth of the channel by 10 db.

- In the OFDM system, this will kill of one of the eight carriers.
But as the underlying interleaving distributes those (one-out-of-eight) error-bits over the complete stream, and that the FEC system is very well capable of correcting one biterror out of 8, the end-result is the the stream is still received error-free
- in the single-carrier  PSK signal, that 10 db "selective qsb" will be spread out over the complete bandwidth, resulting in an overall 1.25 db drop in the S/N ratio, .. so no errors here neither.

2/ image that the selective qsb is not -10 db, but -30.
- In the OFDM system, this actually has the same result.
It is still one carrier out of 8 that is drowned, so -for the overall- is it still 1/8 of the bits lost, something that can be handled by the underlying FEC
- in the single-carrier PSK , the overall interference over the complete is now 3.75 db (30 db/8), which is more then the 3 db margin so the signal is lost.


But, I do know that this is a very theoretical approach with some well-known variables.

Also, a single-carrier PSK system has a better spectral density then OFDM (look at the gap of spectrum in between the carriers that isn't used, and there it the guard-interval in the time-domain), so the actual usable raw bitrate of a OFDM will always be lower then a pure single-PSK carrier.



My impression is that OFDM systems are good at dealing with where where interference at one very precise specific frequency.


NB: Reaching the limitation of psk,  the  lower  levels  revert to   mfsk , simply as during  trials ,  high  latitude users
encountered link  survival issues  coupled to  psk modulation , mfsk provides ''the'' most   robust and  energy efficient
modem ,
Interesting.
What is the reason for this and why at higher latitude? More multipath? More selective qsb?



Hope that  fills in some of the  gaps ,
Well, I haven't really looked at HF datacommunication up to now.

It's interesting to learn how the radio-channel on HF compares / differs from on VHF/UHF, and what techniques are used to deal with them.


73-Graham
g0nbd
73

kristoff - on1arf


Re: Understanding APSK and QAM Rohde and Schwartz video #VARA

Graham
 

On Mon, Aug 9, 2021 at 08:13 PM, Kristoff Bonne wrote:
use a combination of QAM and APSK constelation
Kristoff

Its never immediately  obvious , from the  video,  the  issues round  the  pk-pk  levels of the  vara  modem are  perhaps , a little more  translucent  [as opposed to  transparent ] as are the  various  displays .. 

The hybrid serves to  maximise the  pay load of a  single  carrier ,  perhaps more  fragile, but ,  that's  linked to  the rate ,  the  faster , with the  same  energy , then the  higher  becomes the  errors , either  reduce the  rate ,  more  energy/time ..or  increase the  energy , again  more  energy , just the  rate of supply  increases ..

So, is the  issue with  single  high  speed  carriers ,  quite  incompatible with  turbulent  conditions  encountered  on HF
one  single  jamming  signal in the  pass band and everything  stop's  ,higher rates fall  over due to  delays and  multi path  etc ..

then comes the  maximum  rate  compatible with HF ,

Its reasonable , to  take a  guide from the  vara  modem , the maximum rate for  HF is nearly  x10 slower than the  300 baud  limit , quoted as  a limiting  factor  , 300 providing a b/w limitation  , for  single  carrier  systems ,  under ideal  conditions ,  anything and  everything  works ,  DRM broadcast requires , direct or  single  hop  , anything  after ,  then  it fails to  'lock'  
[ as the  sun spot cycle  progresses , the  opportunity for  multiple hop connections will  increase]

B/W utilisation , Much the  same as  say a   Tank with  tracks , and multiple wheeled  vehicle , one track  off ,  stops,  one  tyre  off  , keeps  going ..

Taking the vara   modem has the  optimum   single  carrier  rate  for  HF ,

Then ,  as can be seen,  in the  OFDM  levels,  multiple  low rate  carriers   , are  combined , to  provide ,  maximum  rate,  maximum  ''in channel ''  jamming /  qrm rejection , where as the  on-air  carrier spectrum's  are   provided with  16 ? fixed  patterns ,   not  seen, in the  coding  of the  modem is the  mathematical  'engine' that seeks to  distribute the  payload  , making  best  use the  the  available  channel b/w  and recover it post demodulation . 

.selective  qsb  can  remove  sections the  b/w, but  as long as the  minimum  criteria is met , for the  recovered  data , the  pay-load can be  extracted   if not ,  a more  robust  level  can be  selected , or vice versa 

NB: Reaching the  limitation of psk,  the  lower  levels  revert to   mfsk , simply  as during  trials ,  high  latitude users
encountered link  survival issues  coupled to  psk modulation ,  mfsk provides ''the'' most   robust and  energy efficient 
modem , 

Hope that  fills  in some of the  gaps , 

73-Graham
g0nbd 

.










 


Re: Understanding APSK and QAM Rohde and Schwartz video #VARA

Kristoff Bonne
 

Hi Steve,


First of all, I am still pretty new to learning digital communication.
(currently playing around in GNU Radio trying to learn PSK demodulation ...).


Thank you for your reply.
First of all, no problem to get into the details. That's usually the best way to learn things.


I am however a bit surprised. The video-article you mentioned was about the modulation-scheme of a single-carrier (QAM vs APSK).
How is the issue of single-tone vs. parallel tone (i guess this is 'single-carrier' vs OFDM) you mention in your message below related to this?



On to the discussion of QAM vs APSK.
As you say, the main goal is to get as much bps over a radio-channel.
As is mentioned in the video, the more you cram bits closer together, the less robust the signal is to noise. (isn't it that you need 3db S/N per extra bit you want to cram into one symbol?)

If we are talking about data-communication, you have no knowledge about the data being carried, which means that all bits are considered to be equally important.  In that scenario, the most logical form is create a constellation in which all bits are equality spaced, i.e. a square.
If I look at the constellation of AFSK, the bits are much closer together then in QAM, so this is a clear advantage of QAM over AFSK.

Now, according the video, the advantage of AFSK over QAM is that you can use non-linear amplifiers; as any non-linearity will just result in the 'circles' of the APSK constellation being more spread out which is something that can easily be detected


As said, I am far from an expert on digital communication but I did read about 'data-aided' techniques where the sender emits certain known data-pattern which allow the receive to determine the characteristics of the radio/receiver channel and 'retune' itself if needed. (think of the 'pilot-tones' in OFMD that act as PSK references)
I do not understand why this principle can not be used here (QAM) too. If the transmitter sends out certain predetermined QAM-patterns beforehand, it should allow the receiver to determine if the is an issue with non-linearity of the transmitter and adapt itself.
So I am not sure what is really the advantage of APSK over QAM.


Concerning the discussion below, if I correct, the discussion is about single-carrier vs OFDM.
As far as I understand it, the big advantage of ODFM over single-carrier is related to multipath, especially in mobile-communication in VHF and above. (which is why T-DAB and DVB-T use OFDM).
I cannot really comment on the logic of OFDM on HF, but I am still amazed how multipath can really 'suck out' part of a radio-channel on HF. Just look at what it does to the signal of a DRM transmission!

I guess the main difference between OFDM and single-carrier on HF, is that n OFDM selective multipath will take out one or a few carriers completely, not affecting the other carriers; while on a wideband PSK signal, the interference is "spread-out" over the complete carrier so that all bits are impacted, but less so.
It probably depends on how the underlying error-correction mechanisms deal with this if this has an impact on the actual BER or not.



If I am correct, ISB, 2-ISB, 4-ISB (at least in this context) is dynamically allocating multiple adjacent channels and use it as one single channel. Is this correct?

In that context, it looks to me like the 40, 80 or 160 MHz 'wide' channels in 802.11n and 802.11ac WiFi on 5 GHz.
(I've always been amazed on how they can actually build wifi-chips which can process 160 MHz of bandwidth at once!) Just image the ADC and the processing-power to process that much bandwidth at once!


What are 'burst waveform techniques'?
I do not know that term.



Kristoff - ON1ARF

On 09.08.21 22:34, ALE wrote:

Hi Kristoff ,

Without getting into the complex details as to why,  In the Military as well as a number of Commercial and even some Amateur Radio waveforms these days, as you strive to increase the Over the Air data rate throughput you need to work with more complex forms of modulation to either increase the number of data bits per symbol or more densely pack it, especially with Serial (Single) Tone modems which are now predominate I Military communications as they are superior to Parallel tone modems. With Parallel tone modems you can increase the throughput by just adding more carriers or increasing the symbol rate for a given form of modulation, But many designers have been maintaining the number of carriers and symbol rate and implementing more complex modulation.

There are many challenges and tradeoffs involved. The Military basically hit the wall with Serial tone modems as they did with Parallel tone waveforms. At 256-QAM they did something new and old again, they sort of dusted off the Parallel waveform approach without actually going there and add a few new twists. They took the serial tone modem and started running it on ISB, then 2-ISB and then 4-ISB. Then they went to what is called Wideband, they allocate 24kHz and now 48kHz channels where the actual in use channel starts where not occupied, say the first or 2nd 3kHz portion and extends continuously where not occupied until the full bandwidth id reached iif possible. The PSK carrier is placed where appropriate for the resulting bandwidth occupied. This is the approach taken with MIL-STD-188-110D Appendix D and 4G ALE to MIL-STD-188-141D Appendix G.

Bach to a less than 3kHz channel in the Commercial modem world, some dozen years ago now SCS seen the futility iwth Parallel modems and went to serial tone for PACTOR IV, implementntig aspects found in a number of Military waveforms as they had done with PACTOR III prior. They get into QAM for the highest throuhput as does STANAG 4539 and use Burst waveform techniques as does 3G ALE in STANAG 4538. They lowered the symbol and center of the PSK carrier from that of the Military to fit Commercial and Amateur SSB filter bandwidth. This was all achieved under the guidance of the most reknowned German STANAG modem engineer. That coupled withe SCS Memory AQR provided SCS with the then best and still best in a 3kHz only channel HF modem available, better than the STANAG and MIL-STD modems in a 3kHz channel in my opinion.

In Amateur Radio, at least here in the U.S. we are ham strung by the 300 baud symbol rate limitation imposed by the FCC. Thus serial tone modems cannot be exploited, Parallel tone modems are the only only approach to achieve high throughput.

/s/ Steve, N2CKH

At 03:13 PM 8/9/2021, you wrote:
Hi,


I'm a bit puzzled about this.

After watching the video, I I understand that QAM and APSK are two different systems, each with their advantages and disadvantages, and either with the specific usecase.

So I do not understand why combining QAM and APSK is then a good idea. You mix systems, therefor creating something that has the disadvantages of both.



What is the technical argument for these mil-comm systems to use a combination of QAM and APSK constelation?



Kristoff (on1arf)


On 06.08.21 19:01, ALE wrote:

Hi Graham,

QAM is fun, working to develop Military data modem and ALE serial tone modem QAM waveforms.

In my attached photo the QAM waveform in the constellation display is an MS110B offering, going into MS110C/D Appendix D and 4G ALE get even more complicated, I have not made it to 256-QAM yet, the Appendix waveforms and 3G ALE are in my near future however.

The SCS P4 serial tone modem stops at 32-QAM in less than a 3kHz channel, but the Military waveforms hit a the much higher QAM  count and throughput in a 3kHz channel and then can increase the bandwidth and shift the PSK carrier up to incrementally increase the throughput.

My friend Dario maintains an excellent easy to understand technical blog on pretty much all the waveforms to be found on HF if one is interested in those subject matters at:

http://i56578-swl.blogspot.com/

<http://i56578-swl.blogspot.com/>/s/ Steve, N2CKH

At 02:21 PM 7/3/2021, you wrote:
R&S  , Useful series of  videos covering  aspects of radio
This video  is applicable to the  VARA modem  coding ,
makes  sense of the  displays  -

73-Graham
g0nbd


This video provides an introduction to the basic concepts of amplitude and phase shift keying (APSK) and quadrature amplitude modulation (QAM).
You-tube link :-

Understanding APSK and QAM <https://www.youtube.com/watch?v=1xGncBvWv6U>





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